The various types of faceted Si dendrites observed on splat-quenched surfaces were analyzed in order to understand why the growth direction and morphology of the facet Si dendrites changed with increasing undercooling. The growth directions of typical facet dendrites were determined to be <211>, <110> and <100> using an electron backscatter pattern apparatus. It was found that both the <211> and <110> dendrites with twins were bounded by atomically smooth {111} planes. Therefore, their growth was governed by the incorporation of atoms at re-entrant corners formed by twins. The <100> dendrites with fourfold symmetry had no twins and were commonly observed at high undercoolings. Moreover, two kinds of <100> dendrites with different secondary arm directions <100> and <110> were clarified for the first time. The dendrite tip shape and facet planes, as determined using an atomic force microscope, suggested that the <100> dendrites were bounded by atomically rough {110} and {100} planes. That is, facet Si dendrites varied in their growth direction and morphology with increasing undercooling because the dendrites select atomically rough interfaces in order to promote the incorporation of atoms at high undercoolings.

Growth Mechanism of Twin-Related and Twin-Free Facet Si Dendrites. K.Nagashio, K.Kuribayashi: Acta Materialia, 2005, 53[10], 3021-9